Heretofore, various UV absorbers such as the benzophenones, benzotriazoles and resorcinol monobenzoates have been incorporated into polymers as discussed in Plastics Additives Handbook, Hanser Publishers, Library of Congress Catalog No. 83-062289, pp. 128-134, for use in absorbing or screening deleterious radiation. The additives function well to screen radiation in the range of from about 300 to about 350 nm, however, this range is not adequate to protect the contents of food packaging employing these polymers. Moreover, these compounds when added to polyesters are extractable by solvents which may be present in food packaged with the polymers. Such solvents would include typical food acids, alcohols and the like. Furthermore, these compounds are not in general stable under the polyester manufacturing and processing conditions and produce objectionable yellow shades in food packaging. Also, the various copolyesters such as disclosed in U.S. Pat. No. 4,338,247, while having essentially nonextractable UV absorbers, are not suitable for food packaging in that the abosrbers transmit harmful radiation and are not designed to protect food.
U.S. Pat. No. 3,634,320 discloses compounds somewhat similar to applicant's for mixing into various polymers for U.V. absorption, however, copolymerization is not involved and the .lambda. max values for the compounds are not sufficiently high to protect food. It is noted that the polyfunctional compounds of the patent would act as cross-linking agents in any attempted copolymerization.